Electronic ignition device for internal combustion engines

ABSTRACT

An electronic ignition device for internal combustion engines comprises an ignition distributor having a distributor arm and an ignition circuit connected on the output side with the contact of the distributor arm. The ignition circuit is controlled without contacts by a magnetic pick-up having a rotating armature fixed for rotation with the distributor arm. The armature is formed by a disk carrying a number of permanent magnets corresponding to the number of permanent magnets corresponding to the number of cylinders of the internal combustion engine, the magnets being equally spaced in circumferential direction and disposed at the same radial distance from the axis of rotation of the disk. An induction coil with a soft iron core is disposed at one side of said disk. Upon rotation of the disk with the permanent magnets the exposed pole faces on said side of the disk pass across the end face of the soft iron core. This disposition allows the magnetic pick-up to be mounted within the usual ignition casing equipped with a conventional mechanical interrupter of existing internal combustion engines.

United States Patent Graser et a]. 1451 July 11, 1972 541 ELECTRONICIGNITION DEVICE FOR 3,331,362 7/1967 Mitchell 123/148 E INTERNALCOMBUSTION ENGI S 3,370,190 2/1968 Neapolitakis 123/148 E [72]inventors: Toni Graser, Sonnenhofstrasse, 8340 Hinwil/Zurich; JosephHits, 164, Usterstrasse. 8621 Wetz.kon/Zurich, both of Switzerland (73]Assignee: said Graser, by said Hits [22] Filed: May 18, I970 [21] Appl.No.: 38,340

[30] Foreign Application Priority Data May 21, 1969 Switzerland..7869/69 [52] U.S.Cl. NIB/I48 E, 123/148 R, 123/148F ['51 I Int. Cl.....F02p 1/00 [58] FieldofSear-ch ..l23/l48E [56] References CitedUNITED STATES PATENTS 3,587,551 6/1971 Harrow ..123/l48E 2,353,5277/1944 Touceda 123/148 E 2,984,695 5/1961 Berdine A "123/148 E 3,152,28110/1964 Robbins... .....123/148E 3,184,653 5/1965 Hutson ..123/148 EPrimary Examiner-Laurence M. Goodridge Assistant Examiner-Ronald B. CoxAttomey-Werner W. Kleeman ABSTRACT An electronic ignition device forinternal combustion engines comprises an ignition distributor having adistributor arm and an ignition circuit connected on the output sidewith the contact of the distributor arm. The ignition circuit iscontrolled without contacts by a magnetic pick-up having a rotating armature fixed for rotation with the distributor arm. The arma ture isformed by a disk carrying a number of permanent magnets corresponding tothe number of permanent magnets corresponding to the number of cylindersof the internal combustion engine, the magnets being equally spaced incircumferential direction and disposed at the same radial distance fromthe axis of rotation of the disk. An induction coil with a soft ironcore is disposed at one side of said disk. Upon rotation of the diskwith the permanent magnets the exposed pole faces on said side of thedisk pass across the end face of the soft iron core. This dispositionallows the magnetic pickup to be mounted within the usual ignitioncasing equipped \\ith a conventional mechanical interrupter of existinginternal combustion engines.

13 China, 2 Drawing Figures ELECTRONIC IGNITION DEVICE FOR INTERNALCOMBUSTION ENGINES The invention relates to an electronic ignitiondevice including an ignition distributor, for internal combustionengines, the device having an ignition circuit which is electricallyconnected on the side of the output with the distributor arm contact ofthe ignition distributor and controlled without contacts by a magneticpick-up comprising a rotatable armature driven by the ignitiondistributor shaft, and a fixed induction coil.

The known electronic ignition devices mostly are subsequently built intoautomobiles equipped with conventional ignition systems controlled bymechanical interrupters. In automobiles having rotating pistonandOtto-engines the ignition point is controlled automatically independence of the number of revolutions, in order to obtain the greatestoutput at all operating conditions. The ignition timing device isassembled together with the interrupter and the ignition distributor ina casing, so that it is convenient for saving costs to use these alreadyavailable parts also with electronic built-in ignition circuits, i.e. tolay out the circuit in such manner that it may be connected to themechanical interrupter and the ignition distributor. The advantages ofelectronic ignition devices, however, become fully apparent only whenthese devices are not controlled by contacts, e.g. mechanically by meansof the interrupter, but in contactless manner by a suita ble pick-up.For a contactless control preferably magnetic pick-ups are used, severaltypes of which are known and suitable for insertion into the ignitiondistributor casing. Such known magnetic pick-ups consist for example ofa rotating armature fixed to the distributor shaft having a number ofpermanent magnet poles corresponding to the number of cylinders, thepole surfaces of which are situated in a cylindrical surface coaxialwith the distributor shaft. The magnet armature rotates in an annularstator having a coil connected to the electronic ignition circuit. Inall known distributor constructions, the individual components,particularly the distributor arm and the mechanical interruptor areassembled in a restricted space, so that the interrupter must bedismantled when a magnetic pick-up is built-in, and besides, a certaintype of pick-up can only be used with a definite distributor or with afew types of distributors. This is uneconomical and considerablyincreases the cost of the electronic ignition device. A reduction of thesize of such pick-up structures practically is impossible since thepermanent magnets must have a definite minimum volume in order toguarantee a safe operation at the lower speed ranges (starting speed).

In conventional electronic ignition devices the primary circuit of theignition coil comprises a storage capacitor and a controllablerectifier, preferably a thyristor, as an electronic switching element.The storage capacitor is charged by a com mutator transformer and thethyristor is controlled by a pulse transformer. With a through-connectedthyristor the storage capacitor will be discharged by the primarywinding of the ignition coil, and the high tension pulse induced in thesecondary winding is fed to the distributor. The ignition circuit iscontrolled by control pulses supplied to the pulse transformer. Forgenerating the control pulses either the mechanical interrupter oranother transmitter is used. A magnetic pick-up supplies substantiallysine-shaped control signals from which there are formed control signalsin a pulse shaper. The control pulses shall have steep sides, i.e.practically they shall represent rectangular pulses, and their pulseduration possibly should be shorter than the disconnection time of thethyristor of the ignition circuit. For generating such pulses thesineshaped control signals of the pick-up may be highly amplified inorder to obtain the desired steepness of the sides. Such amplification,however, results in a considerable liability to interference in theignition device, since together with the control signals alsointerference signals are amplified which can lead to an undesiredthrough connection of the thyristor of the ignition circuit. Anelectronic ignition device to be added to an existing device can beproduced economically and operate safely only when the ignitioncharacteristic destined for the respective internal combustion engine isso to say taken over by the electronic device. With the inductivegeneration of pulse signals, however, phase displacements will occur themagnitude of which depends of the ohmic load. For such taking-over ofthe existing ignition characteristic it is a condition that the controlsignals supplied by the pick-up are loaded as little as possible in thepulse shaping stage for generating the control pulses.

Known electronic ignition devices with a magnetic pick-up accordinglyare relatively expensive and often susceptible to trouble, and their usefor subsequent combination with existing ignition systems is limited,the building-in of a magnetic pick-up into a distributor casing beingcomplicated and the original ignition system controlled by themechanical interrupter being completely put out of operation. Thereplacement of an already existing ignition device by a new electronicignition device not only means double expenditure but also theabandonment of an additional safety. Electronic ignition devices havinga magnetic pick-up do not require attendance or servicing and are safein operation. However, should trouble occur, it cannot be dealt withactually by the ordinary service stations. For such cases it would beadvantageous when the original ignition device could be used again.

It is an object of the invention to provide an electronic i gnitiondevice with a magnetic pick-up which can be economically produced, inwhich the magnetic pick-up can be built later on into an existingdistributor casing without having to remove any parts therefrom, andwhich can be mounted with a few manipulations and operates withoutdisturbance.

According to the invention, said armature of the magnetic pick-upcomprises a disk of non-magnetic material mounted on said distributorarm for rotation therewith, a plurality of permanent magnets inserted insaid disk, the number of magnets corresponding to the number ofcylinders of the internal combustion engine, the magnets being uniformlyspaced on the disk in circumferential direction and disposed at equalradial distances from the axis of rotation of said distributor arm, saidmagnets each having one of the pole faces exposed on the side of saiddisk remote of the distributor arm and situated in a plane at rightangles to said axis of the distributor arm, and an induction coil havinga soft iron core provided with an end face adjacent said side of thedisk and arranged so that upon rotation of the disk said exposed polefaces move across said end face of the soft iron core.

In all known ignition distributors the distributor arm comprises a sternfor plugging on the distributor shaft. The disk of the magnet armaturecan be pushed on the stem of the distributor arm and can be connected,for example by means of screws, for rotation therewith. The disctogether with the distributor finger can form a structural unit made ofplastics. In any case the magnet armature of the ignition deviceaccording to the invention only requires a space which hitherto waspresent without being utilized. In a distributor having a mechanicalinterrupter the induction coil with a soft iron core can be fixed to theinterrupter disk without having to remove parts therefrom; thus themechanical interrupter remains fully operative. The induction coil canbe formed by a cylindrical coil and contain a simple straight core whichcan carry a pole shoe having a usual rectangular end face. Theadjustment of the point of ignition preferably is effected by regulatingthe coil on the interrupter disk. For this purpose the induction coilwith the soft iron core can be mounted on a flat clamping plate ofsuitable shape which, when the position of the coil is correctlyadjusted, can be clamped fast by means of screws to the interrupterplate. This also enables a particularly simple mounting of the magneticpick-up upon subsequent introduction into an interrupter casing. Theinduction coil and the permanent magnets can be uniformly dimensionedfor all types of ignition distributors. Only the disks of non-magneticmaterial, e.g. of plastics, are different, which, according to thenumber of cylinders of the respective motor must be equipped with four,six or eight permanent magnets. Such disks which can be fixed todistributor arms preferably are formed as annular disks, the internaldiameter thereof corresponding to the stern diameter of the distributorarm. It has shown that a set of a few different disks will suffice forall current distributor types. The magnetic pick-up of the ignitiondevice accordingly can be manufactured cheaply in series production, itsindividual components, magnet armature with or without distributor arm,induction coil with core and clamping plate being assembled tostructural units made available in commerce for subsequent building in.

In a modification of the invention a transistor amplifier is connectedto the induction coil and is controlled on the input side by the onehalf-waves of the control signal produced when the magnet armaturerotates, while a controllable rectifier having a limiting resistor isconnected to the outputs of the transistor amplifier and an RC-memberconsisting of a capacitor and series connected resistor is connected tothe junction point of the limiting resistor and rectifier, saidcontrollable rectifier being switched through by a reference voltagemember having a lower reference voltage than the operating voltage ofthe transistor amplifier and connected in parallel with said rectifierand with a control electrode, when the output voltage of the amplifierattains the reference voltage, in order to produce via the RC-member,for each of the one halfwaves of the control signal, a control pulse foran ignition circuit connected to the RC-member.

The invention will now be described with reference to the accompanyingdrawings, in which FIG. I diagrammatically shows an ignition distributorof conventional construction with the cover removed and with a built-inmagnetic pick-up of an ignition device according to the invention;

FIG. 2 is a circuit diagram of the electronic ignition device accordingto the invention, equipped with the magnetic pickup of FIG. 1.

The diagrammatic representation of FIG. 1 shows a conventionalarrangement of an ignition distributor, only the distributor arm 1thereof being shown, of a mechanical interrupter and of a centrifugalforce ignition point distributor or timer 9 arranged in a common casing10. The distributor shaft 11 which is rotatably mounted in the casingcarries at its upper end the distributor arm 1, the stem la of which isengaged over the end of the shaft ii. The interrupter cam 12 arranged onthe shaft ll below the distributor arm 1 is shifted in the direction ofrotation in known manner by the centrifugal force ignition point timer9. The interrupter disk 8 extending transversely through the casing 10and carrying the interrupter i3 is situated between the interrupter cam12 and the ignition point timer 9.

A magnetic pick-up for contactless control of an electronic ignitioncircuit is additionally built into the distributor casing 10. Therepresented magnetic pick-up comprises a plane circular ring disk 2 ofplastic having a number of openings corresponding to the number ofcylinders of the respective internal combustion engine, in whichopenings the permanent mag nets 3 are inserted. The permanent magnets 3have a uniform radial distance from the center of the disk and areequally spaced on the disk in circumferential direction. The disk 2 isengaged on the stem la of the distributor arm or finger I and is fixedto the stem, e.g. by screws, for rotation with the shaft. The thicknessof the disk is so chosen that upon rotation and locally acting magneticforces no oscillations will occur.

A cylindrical induction coil 5 having a straight soft iron core 4 isarranged in upright position on the interrupter disk 8 opposite theinterrupter 13. The coil 5 and the core 4 are fixed on a fiat clampingplate 14 which itself can be clamped by means of screws 15 to theinterrupter disk 8. The clamping plate 14 is provided with slots throughwhich pass the screws 15, so that the coil 5 and the soft iron core 4may be shifted over a certain range on the interrupter disk 8 andclamped in a definite position with respect to the contact of thedistributor arm I. Conveniently the clamping plate 14 is provided with acircular arc-shaped slot the mean radius of which is equal to thedistance of the center of a permanent magnet 3 from the axis of rotationof the distributor arm or of the disk 2 and the axis of the coil is inalignment with the middle axis of the slot, so that upon adjustment ofthe coil with correspondingly arranged clamping screws 15, a radialshifting of the coil is not necessary and the end faces 40 of the ironcore are aligned with the path of the rotating permanent magnets 3.

For a satifactory operation of the ignition device it is necessary thatthe permanent magnets have a certain minimum volume. 0n the other hand,it is advantageous in such pick-ups when the pole facing the iron coreof the coil has a narrow pole surface with parallel longitudinal edges,or edges directed radially towards the axis of rotation. For thisreason, blanks of magnet bodies are used which are exactly machined andfinished on one pole only. The openings of the disk 2 will becorrespondingly shaped and the magnet bodies are so inserted into theopenings and cemented therein that the finished pole surfaces areexposed and situated in a plane at right angles to the axis of the disk.

Conducting wires 6 are connected to the ends of the induction coil 5 andare introduced through a cable passage 16 in the casing 10 and connectedwith their other ends to the electrical part of the ignition device. Theelectrical part comprises a pulse shaper stage 17 on the input side,which produces control signals of defined edge steepness from thepractically sineshaped signals supplied from the induction coil 5. Thecontrol pulses are fed to the proper ignition circuit 18. The ignitioncircuit 18 is transistorized and any suitable type of the various knowncircuits can be used.

When the above described ignition device is incorporated in the existingignition system having a mechanical interrupter, the following threemodes of operation are possible: Operation with the mechanicalinterrupter and the originally existing ignition system, operation withthe mechanical interrupter controlled electronic ignition circuit, andoperation with electronic ignition circuit controlled without contactsby the magnetic pick-up. The switching-over from one mode of operationto the other can be effected in a few manipulations by reversing ofconnections; when operating with the electronic ignition device theinterrupter I3 conveniently will be lifted off and clamped in place.

FIG. 2 shows the circuit diagram of the ignition device according to theinvention. As has been described already, the magnetic pick-up consistsof a disk 2 of non-magnetic material which is mounted for rotation withthe stem of the distributor arm 1. A number of permanent magnets 3corresponding to the number of cylinders of the internal combustionengine on which the device is mounted, is inserted in the disk 2. Forexample the south poles of the magnets 3 comprise pole faces 30 whichare exposed on the bottom side of the disk turned away from thedistributor arm 1, and which, upon rotation of the disk 2, travel acrossthe end face 4a of a soft iron core 4 of an induction coil 5 disposedstationary below the disk 2. One end of the induction coil 5 isconnected to the input I of a pulse shaper stage 17. The output A of thepulse shaper stage 17 is connected with the control input E of anignition circuit l8 known per se. The ignition circuit 18 includes aconventional ignition coil 20, across the primary winding of which acapacitor controlled by a thyristor S is discharged. The secondarywinding of the ignition coil 20 is connected by an ignition conductor 22with the contact of the distributor arm 1. Since ignition circuits ofthis type are well known in the art, details thereof are notrepresented.

The pulse shaper stage 17 as shown in the diagram comprises as anamplifier a n-p-n type transistor T, in common emitter circuit. Thenegative pole of the battery 8 is connected by a resistor R, with thebase and by a resistor R, with the emitter of the transistor T Thepositive pole of the battery B is connected to the base by an ignitionswitch 19 and a resistor R and by a resistor R, with the collector ofthe transistor 1",. The base of the transistor T is connected by aresistor R a diode D, and the input terminal I of the pulse shaper stagewith one end of the inductor coil 5, the other end of which is grounded.

The output signals of the amplifier are picked up at the outputs L andM, one output L being connected to the collector and the other output Mto the emitter of the transistor T,. The collector-to-emitter space isbridged by a limiting resistor R, connected to the output L and by athyristor S, connected in series with the resistor R the cathode of thethyristor being connected to the output M. The anode of the thyristor,i.e. the junction point N of the limiting resistor R and the thyristorS, is connected with the one electrode of a capacitor C, the otherelectrode of which is connected by a charging resistor R, with thenegative pole of the battery B. [n the represented example the RC memberformed by the capacitor C, and the resistor R is shown as a part of theinput stage of the electronic ignition circuit 18. The input stagecomprises a pulse amplifier having a n-p-n transistor T in known circuitarrangement. The base of the transistor T is connected to the junctionpoint P of the capacitor C, and the resistor R, of the RC member. Aresistor R, forms together with the resistor R, of the RC member thebase voltage divider for the transistor of the pulse amplifier stage.

A Zener diode 2, with an operating resistor R, is connected in parallelwith the thyristor S, of the pulse shaper stage 17. The cathode of theZener diode Z, is applied to the junction point N of the thyristor S,and the limiting resistor R and the anode of the Zener diode isconnected to the control electrode G of the thyristor S,. A Zener diodeis used having a Zener voltage with a lower value than the operatingvoltage of the transistor amplifier T,, R R Preferably, the Zenervoitage shall not exceed 70 percent of the operating voltage. When thedisk 2 rotates, an essentially sine-shaped signal voltage is induced inthe induction coil 5, however, in contradistinction with known magneticpick-ups no reversal of polarity of the magnetic field occurs. The onehalf-waves of the signal voltage are formed when the magnetic field inthe iron core is created, and the other half-waves are formed when themagnetic field collapses or decays. The load dependent phase shiftalready mentioned occurs when the magnetic field sets up. For producingsignal pulses the front sides of the half-waves are used. The directionof winding of the induction coil and the polarity of the permanentmagnets is so chosen that the halfwaves with positive amplitude areformed when the magnetic field sets up and when the magnetic fielddecays the halfwaves with negative amplitude are formed. The negativehalf waves are then practically independent of the value of the ohmicload. The positive half-waves are suppressed by the diode D, and thenegative half-waves are supplied via the resistor R, ofthe base of thetransistor T,. At each half-wave the voltage at the collector of thetransistor T, rises. When this signal voltage reaches the value of theZener voltage of the Zener diode 2,, i.e. the value of the referencevoltage, then the Zener diode 2, becomes conductive and the thyristor S,is switched through by the control electrode G, so that the capacitor C,of the RC member rapidly discharges and a short negative pulse, forexample ofa duration of 2;; sec, will occur at the junction point P ofthe RC member which pulse is supplied to the base of the transistor T ofthe input pulse amplifier of the ignition circuit 18. When the amplitudeof the input signal voltage at the transistor T, decreases, also thesignal voltage at the collector drops to a minimum, so that thethyristor S, is switched off into non conducting condition and thecircuit is ready for producing a control pulse from the subsequentlyarriving signal half-wave.

The Zener voltage, as already mentioned, does not exceed 70 percent ofthe operating voltage of the transistor amplifier. This guarantees thateven at smallest RPM of the engine, particularly when starting, ignitionsparks will be safely produced.

A further advantage of this ignition device consists in that arevolution counter can be connected to the pulse-shaper stage 17. Forthis purpose the collector of the transistor T, is connected to anoutput terminal F. A commercially available revolution counter RPM canbe connected to the output terminal F by a matching circuit 2]. Thismatching circuit may comprise a n-p-n transistor T, which produces ateach control signal a pulse for the RPM counter by discharging of acapacitor.

The above described pulse shaper renders the electronic ignition devicefully insensitive to interference pulses, so that a safe ignition isguaranteed at low as well as high speed of rotation. Moreover, the pulseshaper is of simple construction and can be manufactured at moderatecost.

While there is shown and described present preferred embodiments of theinvention, it is to be distinctly understood that the invention is notlimited thereto but may be otherwise variously embodied and practicedwithin the scope of the following claims. Accordingly,

We claim:

1. In an ignition distributor for internal combustion engines of thetype having an open housing with a rotatable shaft therein, a rotatabledistributor arm having a lower stem portion for mounting on the end ofsaid shaft, a mechanical interrupter arranged on an adjustable discsupport positioned below said distributor arm, said interrupter beingcontrolled by cam means fixed to said shaft, a cap for said housingcarrying a plurality of contacts in sequential communication with saidarm, the improvement comprising:

a magnetic pickup positioned in said distributor housing with or withoutthe presence of said mechanical interrupter,

said magnetic pickup including a rotatable disc of a nonmagneticmaterial positioned in free space above said interrupter support andsecured to said distributor arm for synchronous rotation by said shaft,

said rotatable disc being provided with a plurality of permanent magnetscorresponding in number to the number of cylinders of the internalcombustion engine, a stationary induction coil mounted below saidrotatable disc on said interrupter support and having a soft iron core,said permanent magnets each having a pole face confronting an end faceof said iron core during rotation of said disc, said permanent magnetsof said disc and said induction coil together with said soft iron corebeing arranged with regard to said disc in such a manner that the polefaces of one magnetic pole of said permanent magnets move past the endface of the soft iron core.

2. The improvement of claim 1 further including pulse shaper meansincorporating a transistor amplifier means and an input means forconnecting said input with said induction coil, said connecting meansincluding a diode and a resistor for connecting one end of the inductioncoil with the base of a transistor of said transistor amplifier means ofsaid pulse shaper means in order to deliver to said transistor thehalfwaves of the signals produced at said induction coil during rotationof the disc when the magnetic field collapses, and an ignition circuitelectrically connected with said pulse shaper means and electricallyconnected at the output side with said distributor arm of said ignitiondistributor and controlled by output pulses of said pulse shaper means.

3. An ignition device according to claim 2, in which said transistoramplifier means connected to said induction coil, is controlled on theinput side by the one half-waves of the control signals produced uponrotation of the magnet armature, and in which a controllable rectifierhaving a limiting resistor is connected to the outputs of the transistoramplifier means, and an RC-member consisting of a capacitor and seriesconnected resistor is connected to the junction point of the limitingresistor and rectifier, said controllable rectifier being switchedthrough by a reference voltage member having a lower reference voltagethan the operating voltage of the transistor amplifier and connected inparallel with said rectifier and with a control electrode, when theoutput voltage of the amplifier attains the reference voltage, in orderto produce via the RC-member, for each of the one half-waves of thecontrol signal, a control pulse for said ignition circuit which isconnected to the RC-member.

4. An ignition device according to claim 3, wherein said transistor ofsaid transistor amplifier means comprises a n-p-n transistor incommon-emitter circuit, said coil being wound in such manner as toproduce half-waves with a negative amplitude upon a decaying magneticfield.

5. An ignition device according to claim 4, wherein said controllablerectifier is formed as a miniature thyristor having an anode connectedby a limiting resistor to the collector of the n-p-n transistor. and acathode connected to the emitter of said transistor. v

6. An ignition device according to claim 5, wherein said referencevoltage member comprises a Zener diode having an anode connected to thecontrol electrode of said miniature thyristor and by a resistor to theemitter of the n-p-n transistor.

7. An ignition device according to claim 6, wherein said Zener diode isconnected in parallel to the anode-control electrode gap, the Zenervoltage of said diode not exceeding 70 percent of the operating voltageof the transistor.

8. An ignition device according to claim 6, wherein the collector of then-p-n transistor is connected to an output ter' minal adapted forconnection with an RPM counter by means of a matching circuit.

9. An electronic ignition device for an internal combustion enginehaving an ignition distributor and an ignition circuit electricallyconnected with the distributor arm of the ignition distributor on theoutput side, said ignition circuit being controlled without contacts bya magnetic pick-up having a rotatable armature and a stationaryinduction coil, wherein said armature of the magnetic pick-up comprisesa disk of non-magnetic material mounted on said distributor arm forrotation therewith, a plurality of permanent magnets inserted in saiddisk, the number of magnets corresponding to the number of cylinders ofthe internal combustion engine, the magnets being uniformly spaced onthe disk in circumferential direction and disposed at equal radialdistances from the axis of rotation of said distributor arm, saidmagnets each having one of the pole faces exposed on the side of saiddisk remote of the distributor arm and situated in a plane at rightangles to said axis of the distributor arm, and an induction coil havinga soft iron core provided with an end face adjacent said side of thedisk and arranged so that upon rotation of the disk said exposed polefaces move across said end face of the soft iron core, a transistoramplifier connected to said induction coil,

said amplifier being controlled on the input side by the one half-wavesof the control signals produced upon rotation of the magnet armature,and in which a controllable rectifier having a limiting resistor isconnected to the outputs of the transistor amplifier, and an RC-memberconsisting of a capacitor and series connected resistor is connected tothe junction point of the limiting resistor and rectifier, saidcontroilable rectifier being switched through by a reference voltagemember having a lower reference voltage than the operating voltage ofthe transistor amplifier and connected in parallel with said rectifierand with a control electrode, when the output voltage of the amplifierattains the reference voltage. in order to produce via the RC-member,for each of the one halfwaves of the control signal, a control pulse forsaid ignition circuit which is connected to the RC-member, transistoramplifier comprising a n-p-n transistor in common-emitter circuit, thebase of which is connected to one end of the induction coil by aresistor and a diode, the coil being wound in such manner as to producehalf-waves with a negative amplitude upon a decaying magnetic field.

10. An ignition device according to claim 9, in which said controllablerectifier is formed as a miniature thyristor having an anode connectedby a limiting resistor to the collector of the n-p-n transistor, and acathode connected to the emitter of the transistor.

11. An ignition device according to claim 10, in which said referencevoltage member comprises a Zener diode having an anode connected to thecontrol electrode of said miniature thyristor and by a resistor to theemitter of the n-p-n transistor,

12. An ignition device according to claim 11 in which the Zener diode isconnected in parallel to the anode-control electrode gap, the Zenervoltage of said diode not exceeding percent of the operating voltage ofthe transistor.

B. An ignition device according to claim 1], in which the collector ofthe n-p-n transistor is connected to an output terminal adapted forconnection with an RPM counter by means of a matching circuit.

1. In an ignition distributor for internal combustion engines of thetype having an open housing with a rotatable shaft therein, a rotatabledistributor arm having a lower stem portion for mounting on the end ofsaid shaft, a mechanical interrupter arranged on an adjustable discsupport positioned below said distributor arm, said interrupter beingcontrolled by cam means fixed to said shaft, a cap for said housingcarrying a plurality of contacts in sequential communication with saidarm, the improvement comprising: a magnetic pickup positioned in saiddistributor housing with or without the presence of said mechanicalinterrupter, said magnetic pickup including a rotatable disc of anonmagnetic material positioned in free space above said interruptersupport and secured to said distributor arm for synchronous rotation bysaid shaft, said rotatable disc being provided with a plurality ofpermanent magnets corresponding in number to the number of cylinders ofthe internal combustion engine, a stationary induction coil mountedbelow said rotatable disc on said interrupter support and having a softiron core, said permanent magnets each having a pole face confronting anend face of said iron core during rotation of said disc, said permanentmagnets of said disc and said induction coil together with said softiron core being arranged with regard to said disc in such a manner thatthe pole faces of one magnetic pole of said permanent magnets move pastthe end face of the soft iron core.
 2. The improvement of claim 1further including pulse shaper means incorporating a transistoramplifier means and an input means for connecting said input with saidinduction coil, said connecting means including a diode and a resistorfor connecting one end of the induction coil with the base of atransistor of said transistor amplifier means of said pulse shaper meansin order to deliver to said transistor the half-waves of the signalsproduced at said induction coil during rotation of the disc when themagnetic field collapses, and an ignition circuit electrically connectedwith said pulse shaper means and electrically connected at the outputside with said distributor arm of said ignition distributor andcontrolled by output pulses of said pulse shaper means.
 3. An ignitiondevice according to claim 2, in which said transistor amplifier meansconnected to said induction coil, is controlled on the input side by theone half-waves of the control signals produced upon rotation of themagnet armature, and in which a controllable rectifier having a limitingresistor is connected to the outputs of the transistor amplifier means,and an RC-member consisting of a capacitor and series connected resistoris connected to the junction point of the limiting resistor andrectifier, said controllable rectifier being switched through by areference voltage member having a lower reference voltage than theoperating voltage of the transistor amplifier and connected in parallelwith said rectifier and with a control electrode, when the outputvoltage of the amplifier attains the reference voltage, in order toproduce via the RC-member, for each of the one half-waves oF the controlsignal, a control pulse for said ignition circuit which is connected tothe RC-member.
 4. An ignition device according to claim 3, wherein saidtransistor of said transistor amplifier means comprises a n-p-ntransistor in common-emitter circuit, said coil being wound in suchmanner as to produce half-waves with a negative amplitude upon adecaying magnetic field.
 5. An ignition device according to claim 4,wherein said controllable rectifier is formed as a miniature thyristorhaving an anode connected by a limiting resistor to the collector of then-p-n transistor, and a cathode connected to the emitter of saidtransistor.
 6. An ignition device according to claim 5, wherein saidreference voltage member comprises a Zener diode having an anodeconnected to the control electrode of said miniature thyristor and by aresistor to the emitter of the n-p-n transistor.
 7. An ignition deviceaccording to claim 6, wherein said Zener diode is connected in parallelto the anode-control electrode gap, the Zener voltage of said diode notexceeding 70 percent of the operating voltage of the transistor.
 8. Anignition device according to claim 6, wherein the collector of the n-p-ntransistor is connected to an output terminal adapted for connectionwith an RPM counter by means of a matching circuit.
 9. An electronicignition device for an internal combustion engine having an ignitiondistributor and an ignition circuit electrically connected with thedistributor arm of the ignition distributor on the output side, saidignition circuit being controlled without contacts by a magnetic pick-uphaving a rotatable armature and a stationary induction coil, whereinsaid armature of the magnetic pick-up comprises a disk of non-magneticmaterial mounted on said distributor arm for rotation therewith, aplurality of permanent magnets inserted in said disk, the number ofmagnets corresponding to the number of cylinders of the internalcombustion engine, the magnets being uniformly spaced on the disk incircumferential direction and disposed at equal radial distances fromthe axis of rotation of said distributor arm, said magnets each havingone of the pole faces exposed on the side of said disk remote of thedistributor arm and situated in a plane at right angles to said axis ofthe distributor arm, and an induction coil having a soft iron coreprovided with an end face adjacent said side of the disk and arranged sothat upon rotation of the disk said exposed pole faces move across saidend face of the soft iron core, a transistor amplifier connected to saidinduction coil, said amplifier being controlled on the input side by theone half-waves of the control signals produced upon rotation of themagnet armature, and in which a controllable rectifier having a limitingresistor is connected to the outputs of the transistor amplifier, and anRC-member consisting of a capacitor and series connected resistor isconnected to the junction point of the limiting resistor and rectifier,said controllable rectifier being switched through by a referencevoltage member having a lower reference voltage than the operatingvoltage of the transistor amplifier and connected in parallel with saidrectifier and with a control electrode, when the output voltage of theamplifier attains the reference voltage, in order to produce via theRC-member, for each of the one half-waves of the control signal, acontrol pulse for said ignition circuit which is connected to theRC-member, transistor amplifier comprising a n-p-n transistor incommon-emitter circuit, the base of which is connected to one end of theinduction coil by a resistor and a diode, the coil being wound in suchmanner as to produce half-waves with a negative amplitude upon adecaying magnetic field.
 10. An ignition device according to claim 9, inwhich said controllable rectifier is formed as a miniature thyristorhaving an anode connected by a limiting resistor to the collector of then-p-n transistor, and a catHode connected to the emitter of thetransistor.
 11. An ignition device according to claim 10, in which saidreference voltage member comprises a Zener diode having an anodeconnected to the control electrode of said miniature thyristor and by aresistor to the emitter of the n-p-n transistor,
 12. An ignition deviceaccording to claim 11 in which the Zener diode is connected in parallelto the anode-control electrode gap, the Zener voltage of said diode notexceeding 70 percent of the operating voltage of the transistor.
 13. Anignition device according to claim 11, in which the collector of then-p-n transistor is connected to an output terminal adapted forconnection with an RPM counter by means of a matching circuit.